High intensity lamps such as mercury, metal halide or high pressure sodium lamps commonly used in lighting fixtures are usually single-ended and have a screw base. While the socket into which the lamp is screwed will locate it and hold it in place, it is desirable to have some additional means to positively locate the lamp in the desired attitude or location relative to the luminaire's design light center. Also in installations subject to vibration it is desirable to have some additional means to counter the effects thereof and prevent the lamp for loosening and possibly fracturing at the socket and falling out. This is particularly desirable in outdoor luminaires, especially street or highway lighting fixtures which are subject to roadway vibration and pole sway caused by wind.
In U.S. Pat. No. 3,694,649--Thompson, Lamp Support Device, a retaining device for countering the effects of vibration is described. It takes the form of a pair of elongated stiff wire members secured to an adjustable lamp socket bracket. These members extend axially to the neck portion of the lamp and have curved end portions which engage the neck while encircling it. In addition to protecting the lamp against vibration-loosening under service conditions, the support device also facilitates relamping. By providing support adequate to retain the lamp in the fixture even after the base is fully disengaged from the socket, the possibility of the lamp being accidentally dropped by the electrician and resultant breakage is greatly reduced.